U.S. patent application number 09/886337 was filed with the patent office on 2002-02-07 for antenna coil for ic card and manufacturing method thereof.
Invention is credited to Kubota, Tadashi, Sakamoto, Hiroyuki, Tada, Hiroshi, Takano, Toshinori, Yasukawa, Hidenori, Yoshimoto, Masami.
Application Number | 20020015002 09/886337 |
Document ID | / |
Family ID | 26594503 |
Filed Date | 2002-02-07 |
United States Patent
Application |
20020015002 |
Kind Code |
A1 |
Yasukawa, Hidenori ; et
al. |
February 7, 2002 |
Antenna coil for IC card and manufacturing method thereof
Abstract
An antenna coil for an IC card includes a base material of a
resin film having the thickness of at least 15 .mu.m and at most 70
.mu.m, and a circuit pattern layer formed on a surface of the base
material, having the thickness of at least 7 .mu.m and at most 60
.mu.m formed of an aluminum foil containing aluminum by at least
97.5 mass % and at most 99.7 mass %. On the surface of the resin
film base material, an aluminum foil containing aluminum is fixed
by using a polyurethane based adhesive layer containing an epoxy
resin, a resist ink layer having a prescribed pattern is printed on
the foil, the foil is etched using the resist ink layer as a mask
to form a circuit pattern layer, and the resist ink layer is
removed.
Inventors: |
Yasukawa, Hidenori; (Osaka,
JP) ; Sakamoto, Hiroyuki; (Osaka, JP) ;
Takano, Toshinori; (Osaka, JP) ; Kubota, Tadashi;
(Osaka, JP) ; Tada, Hiroshi; (Osaka, JP) ;
Yoshimoto, Masami; (Osaka, JP) |
Correspondence
Address: |
FASSE PATENT ATTORNEYS, P.A.
P.O. BOX 726
HAMPDEN
ME
04444-0726
US
|
Family ID: |
26594503 |
Appl. No.: |
09/886337 |
Filed: |
June 21, 2001 |
Current U.S.
Class: |
343/895 ;
343/700MS |
Current CPC
Class: |
G06K 19/0723 20130101;
G06K 19/07784 20130101; H05K 2201/0195 20130101; H05K 3/386
20130101; H05K 1/09 20130101; G06K 19/07779 20130101; H05K
2201/0355 20130101; G06K 19/07749 20130101; G06K 19/07783
20130101 |
Class at
Publication: |
343/895 ;
343/700.0MS |
International
Class: |
H01Q 001/36 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 23, 2000 |
JP |
2000-188592 |
Nov 21, 2000 |
JP |
2000-354383 |
Claims
What is claimed is:
1. An antenna coil for an IC card, comprising: a base material
containing resin and having a thickness of at least 15 .mu.m and at
most 70 .mu.m; and a circuit pattern layer formed on a surface of
said base material, having a thickness of at least 7 .mu.m and at
most 60 .mu.m, formed of a foil containing aluminum of at least
97.5 mass % and at most 99.7 mass %.
2. The antenna coil for an IC card according to claim 1, wherein
said foil contains iron by at least 0.7 mass % and at most 1.8 mass
%.
3. The antenna coil for an IC card according to claim 1, wherein
said foil contains silicon by at least 0.03 mass % and at most 0.5
mass %.
4. The antenna coil for an IC card according to claim 1, wherein
said foil contains silicon by at least 0.03 mass % and at most 0.5
mass %, and copper by at most 0.3 mass %.
5. The antenna coil for an IC card according to claim 1, wherein
said base material includes a resin having thermal contraction
coefficient of at most 0.3% when held at 150.degree. C. for 30
minutes.
6. The antenna coil for an IC card according to claim 1, wherein
said resin is at least one selected from the group consisting of
low profile polyethylene terephthalate and low profile polyethylene
naphthalate.
7. The antenna coil for an IC card according to claim 1, wherein
said circuit pattern layer includes a first circuit pattern layer
formed on one surface of said base material and a second circuit
pattern layer formed on the other surface of said base
material.
8. The antenna coil for an IC card according to claim 7, wherein at
least a part of said first circuit pattern layer is in contact with
at least a part of said second circuit pattern layer penetrating
through said base material.
9. The antenna coil for an IC card according to claim 1, further
comprising an adhesive layer interposed between and bonding said
circuit pattern layer and said base material.
10. The antenna coil for an IC card according to claim 9, wherein
said adhesive layer includes a polyurethane based adhesive
containing an epoxy resin.
11. The antenna coil for an IC card according to claim 1, farther
comprising an underlying coating layer interposed between said
circuit pattern layer and said base material and formed on a
surface of said base material.
12. The antenna coil for an IC card according to claim 11, further
comprising an adhesive layer posed between and bonding said
underlying coating layer and said base material.
13. The antenna coil for an IC card according to claim 12, wherein
said adhesive layer includes a polyurethane based adhesive
containing an epoxy resin.
14. The antenna coil for an IC card according to claim 11, wherein
said underlying coating layer has a thickness of at least 0.1 .mu.m
and at most 5 .mu.m.
15. The antenna coil for an IC card according to claim 11, wherein
said underlying coating layer includes at least one selected from
the group consisting of epoxy based primer, acrylic primer, and
vinyl chloride-vinyl acetate copolymer based primer.
16. A method of manufacturing an antenna coil for an IC card,
comprising the steps of: fixing, on a surface of a base material
containing resin and having a thickness of at least 15 .mu.m and at
most 70 .mu.m, a foil containing aluminum by at least 97.5 mass %
and at most 99.7 mass % and having a thickness of at least 7 .mu.m
and at most 60 .mu.m by using an adhesive; printing a resist ink
layer having a prescribed pattern on said foil; etching said foil
using said resist ink layer as a mask to form a circuit pattern
layer containing aluminum; and after etching said foil, removing
said resist ink layer.
17. The method of manufacturing an antenna coil for an IC card
according to claim 16, wherein said step of fixing said foil
includes fixing said foil on one surface and on the other surface
of said base material, and said step of forming said circuit
pattern layer includes forming a first circuit pattern layer on one
surface of said base material and forming a second circuit pattern
layer on the other surface of said base material.
18. The method of manufacturing an antenna coil for an IC card
according to claim 17, further comprising the step of bringing at
least a part of said first circuit pattern layer into contact with
at least a part of said second circuit pattern layer by a crimping
process.
19. The method of manufacturing an antenna coil for an IC card
according to claim 16, wherein said step of fixing said foil on a
surface of said base material includes, after forming an underlying
coating layer on one surface of said foil, adhering said base
material to a surface of said underlying coating layer, and said
step of printing a resist ink layer having a prescribed pattern on
said foil includes printing of a resist ink layer having a
prescribed pattern on the other surface of said foil.
20. The method of manufacturing an antenna coil for an IC card
according to claim 16, wherein said step of fixing said foil on a
surface of said base material includes fixing said foil on a
surface of said base material using a polyurethane based adhesive
containing an epoxy resin.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an antenna coil for an IC
card and to the method of manufacturing the same. More
specifically, the present invention relates to an antenna coil for
an IC card in which a circuit pattern layer of the antenna coil for
the IC card is formed of an aluminum foil, as well as to the method
of manufacturing the same. Here, the aluminum foil is not limited
to a pure aluminum foil but it also includes an aluminum alloy
foil.
[0003] 2. Description of the Related Art
[0004] Recently, IC cards have been developed remarkably, and the
use of the IC cards is widening to telephone cards, credit cards,
pre-paid cards, cash cards, ID cards and card keys. As a base
material for the conventional IC cards, resin film such as a
polyimide film, a general purpose polyethylene terephthalate (PET)
film or the like has been used. A copper foil or a high-purity
aluminum foil is laminated on each side of the resin film and
subjected to etching, whereby a circuit pattern layer of copper or
aluminum is formed on a surface of the base material, providing an
antenna coil for the IC card.
[0005] The process of etching the copper foil for forming the
circuit pattern layer takes too much time, and therefore production
efficiency is low. Further, after the etching process of the copper
foil, an oxidizing reaction tends to occur at the surface of the
copper foil, making instable the electrical resistance value of the
surface of the circuit pattern.
[0006] When such a resin as described above is used as a base
material of the antenna coil for IC cards and copper foils are to
be laminated on both surfaces of the base material, it is necessary
to attain electrical conduction between the circuit pattern layers
of the copper foils formed on opposing surfaces of the base
material. For this purpose, a plating layer of a through hole is
formed between the circuit pattern layers of the copper foil, or
printing with silver paste is performed. Such process steps lead to
increased cost for manufacturing the antenna coil for IC cards and
lowers production efficiency.
[0007] When a high-purity aluminum foil having the purity of at
least 99.8 mass %) is used as the material for forming the circuit
pattern layer, superior oxidation resistance can be attained.
Etching, however, takes longer time, resulting in low production
efficiency. An IC card having the circuit pattern layer formed by
using the high-purity aluminum foil is susceptible to possible
disconnection of the circuit caused by emboss processing or
imprinting such as inscription provided on the final product, thus
reliability is not very high.
SUMMARY OF THE INVENTION
[0008] An object of the present invention is to provide an antenna
coil for an IC card having superior processability and allowing
higher efficiency of production.
[0009] The antenna coil for an IC card in accordance with the
present invention includes a base material containing resin and
having a thickness of at least 15 .mu.m and at most 70 .mu.m, and a
circuit pattern layer formed on a surface of the base material and
having the thickness of at least 7 .mu.m and at most 60 .mu.m
formed of a foil containing aluminum of at least 97.5 mass % and at
most 99.7 mass %.
[0010] In the antenna coil for an IC card in accordance with the
present invention, the foil constituting the circuit pattern layer
has low aluminum purity, and therefore etch rate to form the
circuit pattern layer can be improved, and hence production
efficiency can be improved. Further, as the circuit pattern layer
contains aluminum of the limited purity as mentioned above, it is
possible to maintain electrical resistance value of the surface
stable over a long time Thus, an antenna coil for an IC card having
higher stability over a long period of time can be attained.
[0011] Preferably, in the antenna coil for an IC card in accordance
with the present invention, the foil constituting the circuit
pattern layer includes iron by at least 0.7 mass % and at most 1.8
mass %.
[0012] Here, as the aluminum foil constituting the circuit pattern
layer contains iron by a limited content, it has such strength and
elongation that lead to superior processability. Therefore, during
the steps of manufacturing the antenna coil for an IC card or
during emboss processing of the final product, possible tearing of
the aluminum foil or disconnection of the circuits can be
prevented. Further, as the etch rate for forming the circuit
pattern layer can be improved, production efficiency can be
improved.
[0013] Preferably, in the antenna coil for an IC card in accordance
with the present invention, the aluminum foil constituting the
circuit pattern layer contains silicon by at least 0.03 mass % and
at most 0.5 mass %.
[0014] Preferably, in the antenna coil for an IC card in accordance
with the present invention, the aluminum foil constituting the
circuit pattern layer contains silicon by at least 0.03 mass % and
at most 0.5 mass % and copper by at most 0.3 mass %.
[0015] The polyimide film used as the base material of the antenna
coil for an IC card is expensive, and in addition it absorbs much
moisture, resulting in variation in electrical characteristic of
the antenna coil during use of the IC card, possibly causing a
malfunction. When a general purpose PET film is used as the base
material of the antenna coil for an IC card, there would be an
undesirable shrinkage as the base material is heated when an IC
chip is mounted on the surface of the circuit pattern layer, for
example. Therefore, dimensional accuracy of the circuit pattern
layer formed on the base material of general purpose PET film
becomes instable, and in addition, smoothness of the base material
deteriorates.
[0016] Therefore, it is preferred that the base material includes a
resin of which thermal contraction when held at 150.degree. C. for
30 minutes is at most 0.3%.
[0017] Here, as the base material includes the resin having such a
limited thermal contraction coefficient, contraction can be
effectively prevented in the step of thermal processing at the time
of mounting the IC chip, for example. Hence, dimensional accuracy
of the circuit pattern layer can be maintained stable and the
smoothness of the base material can also be maintained
satisfactorily.
[0018] Preferably, the resin used as the base material of the
antenna coil for an IC card in accordance with the present
invention is at least one selected from the group consisting of low
profile polyethylene terephthalate (PET) and low profile
polyethylene naphthalate (PEN).
[0019] Preferably, in the antenna coil for an IC card in accordance
with the present invention, the circuit pattern layer includes a
first circuit pattern formed on one surface of the base material,
and a second circuit pattern layer formed on the other surface of
the base material. Here, it is preferred that at least a part of
the first circuit pattern layer is in contact with at least a part
of the second circuit pattern, penetrating through the base
material. This enables electrical conduction between the first and
second circuit pattern layers. Contact between the first and second
circuit pattern layers can be attained easily by a crimping
process.
[0020] Preferably, the antenna coil for an IC card in accordance
with the present invention further includes an adhesive layer
interposed between the circuit pattern layer and the base material
for bonding therebetween. It is preferred that the adhesive layer
includes a polyurethane based adhesive containing an epoxy
resin.
[0021] There is a problem that when the manufactured antenna coils
for the IC cards are stacked on one another or wound as a
belt-shaped roll for shipping or storage, overlapping portions are
adhered with each other hereinafter referred to as blocking).
Therefore, when an IC card is to be manufactured using the antenna
coil, separation of the adhered portions of the antenna coils is
expected to be difficult, possibly stopping the manufacturing
line.
[0022] In order to prevent the blocking, excessive adhesive on the
resin film as the base material should be removed, or a released
paper should be inserted to overlapping portions of the antenna
coil. Perfect removal of the adhesive is very difficult. When a
releasing paper is inserted, an additional step of removing the
release paper becomes necessary in the subsequent manufacturing
process. Therefore, in either case, an additional process step is
required, resulting in increased cost of manufacturing.
[0023] Therefore, it is preferred that the antenna coil for an IC
card in accordance with the present invention further includes an
underlying coating layer formed on the surface of the base
material, inserted between the circuit pattern layer and the base
material. As the underlying coating layer is provided on the
surface of the base material, even when antenna coils are stacked
on one another, the base materials on which circuit pattern layers
are formed are not brought into tight adhesion, as the base
materials are stacked with underlying coatings positioned
therebetween. This prevents blocking. Accordingly, undesired
stopping of the manufacturing line of the IC card can be prevented.
Here, it is further preferred that the antenna coil for an IC card
additionally includes an adhesive layer for bonding positioned
between the underlying coating layer and the base material. The
adhesive layer preferably includes a polyurethane based adhesive
containing an epoxy resin.
[0024] Preferably, in the antenna coil for an IC card in accordance
with the present invention, the thickness of the underlying coating
layer is at least 0.1 .mu.m and at most 5 .mu.m.
[0025] More preferably, the underlying coating layer includes at
least one selected from the group consisting of epoxy based primer,
acrylic primer, and vinyl chloride-vinyl acetate copolymer based
primer.
[0026] The method of manufacturing an antenna coil for an IC card
in accordance with the present invention includes the following
steps.
[0027] (a) On a surface of a base material containing a resin and
having the thickness of at least 15 .mu.m and at most 70 .mu.m,
fixing a foil having the thickness of at least 7 .mu.m and at most
60 .mu.m and containing aluminum of at least 97.5 mass % and at
most 99.7 mass %, by using an adhesive.
[0028] (b) Printing a resist ink layer of a prescribed pattern on
the foil.
[0029] (c) Etching the foil using the resist ink layer as a mask,
to form a circuit pattern layer containing aluminum.
[0030] (d) After etching the foil, removing the resist ink
layer.
[0031] In the method of manufacturing in accordance with the
present invention, the circuit pattern layer is formed by using a
foil having the limited thickness and containing aluminum of the
limited purity as described above, and therefore the time for
etching to form the pattern layer can be reduced. Therefore, it
becomes possible to improve efficiency of production in
manufacturing the antenna coils for IC cards.
[0032] Preferably, in the method of manufacturing an antenna coil
for an IC card in accordance with the present invention, the step
of fixing a foil includes fixing a foil on one surface and on the
other surface of the base material. Preferably, the step of forming
a circuit pattern layer includes the step of forming a first
circuit pattern layer on one surface of the base material and
forming a second circuit pattern layer on the other surface of the
base material.
[0033] Preferably, the method of manufacturing an antenna coil for
an IC card in accordance with the present invention further
includes the step of bringing at least a part of the first circuit
pattern layer into contact with at least a part of the second
circuit pattern layer by a crimping process. Here, in order to
establish electrical conduction between the first and second
circuit pattern layers formed on opposing surfaces of the base
material, it is possible to bring into contact at least parts of
the first and second circuit pattern layers by the crimping
process, and hence conduction can be established through a simple
process step. Therefore, as compared with the conventional method
of manufacturing, manufacturing cost can be reduced and production
efficiency can be improved.
[0034] The method of manufacturing an antenna coil for an IC card
in accordance with another aspect of the present invention includes
the following steps.
[0035] (a) Forming an underlying coating layer on one surface of an
aluminum foil.
[0036] (b) Fixing a base material containing a resin on a surface
of the underlying coating layer.
[0037] (c) Printing a resist ink layer having a prescribed pattern
on the other surface of the aluminum foil.
[0038] (d) Etching a part of the aluminum foil using the resist ink
layer as a mask to form a circuit pattern layer.
[0039] (e) After etching the part of the aluminum foil, removing
the resist ink layer.
[0040] Preferably, in the method of manufacturing an antenna coil
for an IC card in accordance with the present invention, the step
of fixing a base material on the surface of the underlying coating
layer includes the step of fixing the base material on a surface of
the underlying coating layer using a polyurethane based adhesive
containing an epoxy resin.
[0041] Preferably, in the method of manufacturing an antenna coil
for an IC card in accordance with the present invention, the step
of fixing the base material includes adhering one surface of the
base material onto a surface of the underlying coating layer formed
on one surface of a first aluminum foil and adhering the other
surface of the base material onto a surface of the underlying
coating layer formed on one surface of a second aluminum foil, and
the step of forming the circuit pattern layer includes forming the
first circuit pattern layer by etching a part of the first aluminum
foil on one surface of the base material and forming a second
circuit pattern layer by etching a part of the second aluminum foil
on the other surface of the base material. It is needless to say
that the etching of a part of the first aluminum foil and etching
of a part of the second aluminum foil may be performed
simultaneously.
[0042] As described above, the antenna coil for an IC card in
accordance with the present invention is suitable for mass
production at a low cost with high efficiency, and has superior
processability, dimensional accuracy, heat resistance, stability
over time and practical strength. Therefore, the antenna coil can
be provided as a component for an IC card that has high reliability
and capable of exhibiting stable performance over a long period of
time.
[0043] Further, the antenna coil for an IC card in accordance with
the present invention ensures smooth pay off or supply leaf by leaf
without blocking. Therefore, lowering of productivity in the
subsequent step of the manufacturing line of the IC card can be
prevented.
[0044] The foregoing and other objects, features, aspects and
advantages of the present invention will become more apparent from
the following detailed description of the present invention when
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0045] FIG. 1 is a plan view showing an antenna coil for an IC card
in accordance with one embodiment of the present invention.
[0046] FIG. 2 is a partial cross sectional view taken from the
direction of line II-II of FIG. 1.
[0047] FIGS. 3 to 6 are partial cross sectional views showing in
order the steps of manufacturing an antenna coil for an IC card in
accordance with one embodiment of the present invention.
[0048] FIG. 7 is a photomicrograph of a cross section showing parts
of aluminum foils, positioned on opposing sides of a resin film as
the base material, brought into contact with each other in an
antenna coil for an IC card in accordance with the present
invention.
[0049] FIG. 8 is a photomicrograph showing in further enlargement a
portion of the cross section of FIG. 7.
[0050] FIG. 9 is a schematic illustration of the cross section
corresponding to FIG. 7.
[0051] FIG. 10 is a schematic illustration of the cross section
corresponding to FIG. 8.
[0052] FIG. 11 shows an antenna coil for an IC card in accordance
with another embodiment of the present invention, which is a
partial cross section taken along the line of II-II of FIG. 1.
[0053] FIGS. 12 to 16 are partial cross sectional views showing in
order the steps of manufacturing an antenna coil for an IC card in
accordance with another embodiment of the present invention.
[0054] FIG. 17 is a photomicrograph of a surface of sample A etched
at a temperature of 35.degree. C. for 124 seconds.
[0055] FIG. 18 is a photomicrograph of a surface of sample C etched
at a temperature of 35.degree. C. for 124 seconds.
[0056] FIG. 19 is a photomicrograph of a surface of sample A etched
at a temperature of 45.degree. C. for 52 seconds.
[0057] FIG. 20 is a photomicrograph of a surface of sample C etched
at a temperature of 45.degree. C. for 52 seconds.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0058] FIG. 1 is a plan view of the antenna coil for an IC card in
accordance with one embodiment of the present invention, and FIG. 2
is a partial cross sectional view taken along the direction of
II-II of FIG. 1.
[0059] As can be seen from FIGS. 1 and 2, an antenna coil 1 for an
IC card includes a resin film base material 11, adhesive layers 12
formed on opposing sides of resin film based material 11, and
circuit pattern layers 13 formed of an aluminum film, in accordance
with a prescribed pattern on a surface of the adhesive layers 12.
The circuit pattern layer 13 is formed in an eddy pattern on the
surface of the base material as shown in FIG. 1. At an end portion
of circuit pattern layer 13, areas 13c and 13d are formed, on which
an IC chip is mounted. The circuit pattern layer denoted by the
dotted line in FIG. 1 is positioned on the rear surface of base
material 11. The circuit pattern layer 13 formed on the surface of
the base material 11 is in contact with the circuit pattern layer
13 formed on the rear surface of base material 11 to be
electrically conductive at pressure contact portions 13a and 13b,
respectively. The contact is realized by partially destroying the
base material 11 and the adhesive layer 12 by the crimping
process.
[0060] In the above described one embodiment, it is preferred that
the aluminum foil used for the circuit pattern layer 13 has the
thickness of at least 7 .mu.m and at most 60 .mu.m, and that
aluminum purity is at least 97.5 mass % and at most 99.7 mass %.
More preferably, the thickness should be at least 15 .mu.m and at
most 50 .mu.m, and aluminum purity is at least 98.0 mass % and at
most 99.5 mass %.
[0061] When the thickness of the aluminum foil is smaller than 7
.mu.m, pin holes are generated in large number, and there is a
possibility that the foil is torn in the steps of manufacturing.
When the thickness of the aluminum foil exceeds 60 .mu.m, etching
process to form the circuit pattern layer 13 increases and the cost
of the material increases.
[0062] When the purity of aluminum is lower than 97.5 mass %, the
impurity contained in the aluminum foil is too large, resulting in
too high electrical resistance of circuit pattern layer 13 and
significantly degrades corrosion resistance, possibly allowing
corrosion with only a small amount of moisture. When the purity of
aluminum exceeds 99.7 mass %, corrosion resistance of the aluminum
foil is improved too much, resulting in longer time of etching.
[0063] More specifically, as the material of circuit pattern layer
13, pure aluminum foil or aluminum alloy foil such as 1030, 1N30,
1050, 1100, 8021 and 8079 in accordance with JIS (AA)
representation may be used.
[0064] In the present invention, purity of aluminum refers to a
value obtained by subtracting a total mass % of main impurity
elements including iron (Fe), silicon (Si), copper (Cu), manganese
(Mn), magnesium (Mg), zinc (Zn), gallium (Ga), titanium (Ti),
zirconium (Zr), nickel (Ni) and chromium (Cr) from 100 mass %.
[0065] Preferably, the content of iron (Fe) is 0.7 to 1.8 mass %.
In the aluminum foil, preferably, iron content is 0.7 to 1.8 mass
%, silicon (Si) content is 0.03 to 0.5 mass %, and more preferably,
iron content is 0.7 to 1.8 mass %, silicon content is 0.03 to 0.5
mass % and copper (Cu) content is at most 0.3 mass %.
[0066] When the thickness of the aluminum foil is smaller than 7
.mu.m, pin holes are generated in large number, and there is a
possibility of tearing of the foil during the steps of
manufacturing. When the thickness of the aluminum foil exceeds 60
.mu.m, the etching process for forming circuit pattern layer 13
takes much time, and the material cost increases.
[0067] The iron content is preferably in the range of 0.7 to 1.8
mass % in view of etch rate, strength and elongation of the
aluminum foil, and more preferable range is 0.8 to 1.4 mass %. When
iron content is smaller than 0.7 mass %, strength and elongation of
the aluminum foil decrease, possibly causing tearing of the
aluminum foil and disconnection of the circuitry during the steps
of manufacturing or at the time of emboss processing of the final
product, and in addition, etch rate becomes extremely low,
deteriorating production efficiency. When iron content exceeds 1.8
mass %, coarse iron based compound generates, lowering elongation
of the aluminum foil and rolling characteristic during
manufacturing of the aluminum foil.
[0068] The preferable range of silicon content is 0.03 to 0.5 mass
% and more preferable range is 0.05 to 0.3 mass %. When silicon
content exceeds 0.5 mass %, crystal grain tends to be larger,
possibly lowering strength and elongation of the aluminum foil.
When silicon content is smaller than 0.03 mass %, crystal grain
refining effect is saturated, while manufacturing cost is
increased.
[0069] Preferable copper content is at most 0.3 mass %. When copper
content exceeds 0.3 mass %, corrosion resistance of the aluminum
foil degrades significantly, causing excessive etching and shorter
life of IC card. Though the lower limit of copper content is not
specifically defined, it may be about 0.005 mass %. When the
content is smaller than 0.005 mass %, corrosion resistance is
unchanged, while manufacturing cost is increased.
[0070] In the aluminum foil, contents of each element of the main
impurities including manganese (Mn), magnesium (Mg), zinc (Zn),
gallium (Ga), titanium (Ti), zirconium (Zr), nickel (Ni) and
chromium (Cr) may be at most 0.1 mass % and in total, 0.3 mass %.
When the contents of the impurity elements exceed these values,
electric resistance value of the circuit pattern layer excessively
increases, performance of the circuitry degrades, and mechanical
characteristics such as elongation, emboss processing property and
rolling property are possibly degraded. The aluminum matrix may
include, as long as the effects of the present invention can be
attained, unavoidable impurity elements and a small amount of
impurity elements such as boron (B), potassium (K), sodium (Na),
chloride (Cl) and calcium (Ca) other than those listed above.
[0071] Preferably, the aluminum foil has tensile strength of 70 MPa
to 120 MPa and the elongation of at least 4%. When tensile strength
and elongation of the aluminum foil are within these ranges, warp
or crease is not generated during manufacturing or during use, and
therefore there is no possibility of degrading dimensional accuracy
of the circuit pattern layer. Further, as there is no possibility
of tearing or disconnection, a highly reliable IC card can be
provided. The aluminum foil used should preferably be an annealed
foil or a semi-annealed foil, and one prepared by rolling to a foil
followed by annealing at a temperature of about 250 to about
550.degree. C. is preferred. When a hard aluminum foil having
tensile strength exceeding 120 MPa is used, rolling oil tends to
remain, and flexibility (rolling property) and processability are
unsatisfactory.
[0072] A resin film used as the base material of the antenna coil
for an IC card in accordance with the present invention is
preferably at least one selected from the group consisting of
polyethylene (high density polyethylene, low density polyethylene,
linear low density polyethylene and the like), polypropylene,
polyethylene terephthalate, polyethylene naphthalate, nylon, vinyl
chloride, a low profile polyethylene terephthalate (PET) film, a
low profile polyethylene naphthalate (PEN) film and the like. Among
these, more preferably, the resin is at least one selected from a
low profile polyethylene terephthalate (PET) film and a low profile
polyethylene naphthalate (PEN) film. It is preferred that the resin
film has the thickness in the range of 15 to 70 .mu.m and more
preferably in the range of 20 to 50 .mu.m. When the thickness of
the base material is smaller than 15 .mu.m, rigidity of a stacked
body with the aluminum foil forming the circuit pattern layer is
insufficient, resulting in difficulty in working during the
manufacturing steps. When the thickness of the base material
exceeds 70 .mu.m, it may be difficult to surely perform the
crimping process, which will be described later.
[0073] It is preferred that the resin film used for the base
material has thermal contraction coefficient of at most 0.3% when
held at 150.degree. C. for 30 minutes. When thermal contraction
coefficient exceeds 0.3%, there arises a problem that dimensional
accuracy of the circuit pattern layer formed on the base material
is deteriorated.
[0074] The thermal contraction coefficient used in the present
invention refers to the ratio of linear shrinkage percentage, which
is calculated in accordance with the following equation. 1 thermal
contraction coeffeicient ( % ) = L 0 - L L 0 .times. 100
[Equation1]
[0075] In the equation, L represents the length of the resin film
when held at 150.degree. C. for 30 minutes, and L.sub.0 represents
original length of the resin film.
[0076] Adhesion of the aluminum foil for forming the circuit
pattern layer and the resin film as the base material is preferably
realized by dry lamination using a polyurethane (PU) adhesive
containing an epoxy resin. As the polyurethane adhesive containing
an epoxy resin, AD506, AD503, AD76-P1 or the like manufactured by
Toyo-Morton, Ltd. may be used. As a curing agent, CAT-10
manufactured by the same company may be used, mixed at the ratio of
adhesive: curing agent=2 to 12:1. When a common polyurethane
adhesive not containing an epoxy resin is used, delamination tends
to occur during etching for forming the circuit pattern layer or at
the time of mounting the IC chip. This is because the polyurethane
adhesive not containing an epoxy resin has inferior chemical
resistance or heat resistance.
[0077] In order to adhere the aluminum foil for forming the circuit
pattern layer on the resin film as a base material, it is preferred
that the polyurethane based adhesive containing an epoxy resin is
applied by about 1 to about 15 g/m.sup.2 by weight after drying.
When the applied amount is smaller than 1 g/m.sup.2, adhesiveness
of aluminum foil is insufficient. When the amount exceeds 15
g/m.sup.2, the crimping process, which will be described later, is
hindered and manufacturing cost increases.
[0078] One embodiment of the method of manufacturing an antenna
coil for an IC card in accordance with the present invention will
be described in the following. FIGS. 3 to 6 are partial cross
sections showing the steps of manufacturing the antenna coil for an
IC card in accordance with the present invention. FIGS. 3 to 6 are
partial cross sections viewed from the direction along the line
II-II of FIG. 1.
[0079] As can be seen from FIG. 3, an adhesive layer 12 is formed
on each surface of resin film base material 11, and by the adhesive
layer 12, aluminum foil 130 is fixed on each surface of resin film
base material 11. In this manner, a stacked body of aluminum foils
130 and resin film base material 11 is prepared.
[0080] Referring to FIG. 4, a resist ink layer 14 is printed on the
surface of aluminum foil 130 so as to have a prescribed eddy
pattern in accordance with the specification of the antenna coil.
After printing, the process for curing resist ink layer 14 is
performed.
[0081] Referring to FIG. 5, using resist ink layer 14 as a mask,
aluminum foil 130 is etched, whereby a circuit pattern layer 13 is
formed.
[0082] Thereafter, as shown in FIG. 6, resist ink layer 14 is
removed.
[0083] Finally, crimping process is performed at a prescribed area
of circuit pattern layer 13 by using a metal plate having recesses
and protrusions and a metal protrusion, whereby a contact portion
or a pressure contact portion 13a of the circuit pattern layer is
formed, as shown in FIG. 2. In this manner, antenna coil 1 for an
IC card in accordance with the present invention is completed.
[0084] The resist ink used in the method of manufacturing in
accordance with the present invention is not specifically limited.
Preferably, an ultraviolet curing resist ink mainly consisting of
an alkali soluble resin and an acryl monomer having at least one
carboxyl group in the molecule is used. The resist ink allows for
gravure printing, has acid resistance and it can be removed easily
by an alkali, Therefore, the resist ink is suitable for continuous
mass production. By performing gravure printing in a prescribed
circuit pattern on an aluminum foil using the resist ink, curing
the pattern by irradiating with ultraviolet ray, and removing the
resist ink layer through a common method such as acid etching of
the aluminum foil using ferric chloride and removal of the resist
ink by an alkali such as sodium hydroxide, the circuit pattern
layer can be formed.
[0085] An acryl monomer having at least one carboxyl group
includes, for example, 2-acryloyloxyethyl phthalic acid,
2-acryloyloxyethyl succinic acid, (2-acryloyloxyethyl) hexahydro
phthalic acid, 2-acryloyloxypropyl phthalic acid,
(2-acryloyloxypropyl) tetrahydro phthalic acid and
(2-acryloyloxypropyl) hexahydro phthalic acid. Of these, a single
acryl monomer or a mixture of two or more acryl monomers may be
used. The aforementioned alkali soluble resin includes
styrene-maleic acid copolymer resin, styrene-acrylic acid copolymer
resin, and rosin-maleic acid copolymer resin.
[0086] In addition to the components listed above, a common
monofunctional acrylic monomer, a multifunctional acrylic monomer
or a prepolymer may be added to an extent that does not hinder
alkali removability, and it can prepared by appropriately adding a
photopolymerization initiator, a pigment, an additive, a solvent or
the like. The photopolymerization initiator includes benzophenone
and derivative thereof, benzyl, benzoin and alkylether thereof,
thioxantone and derivative thereof, RUSIRIN TPO, IRGACURE
manufactured by Ciba Speciality Chemicals Inc., ESACURE
manufactured by FRATTERI RAMBERTY? may be used. As the pigment, a
color pigment may be added to provide visibility of the pattern, or
an extender pigment such as silica, talc, clay, barium sulfate,
calcium carbonate or the like may be additionally used.
Particularly, silica has an effect of preventing blocking, when the
aluminum foil is to be rolled with the ultraviolet ray curing
resist ink remaining thereon. As an additive, polymerization
inhibiter such as 2-tertiary butyl hydroquinone, silicon, fluorine
compound, antifoaming agent such as acryl polymer, and a levelling
agent are included, which may be appropriately added as needed. The
solvent includes ethyl acetate, ethanol, denatured alcohol,
isopropyl alcohol, toluene, MEK and the like, of which one may be
used, or two or more of these may be used mixed with each other. It
is preferred that the solvent is evaporated away from the resist
ink layer by hot air drying or the like, after gravure
printing.
[0087] After the circuit pattern layer is formed, crimping process
is performed at a room temperature at a prescribed position, so as
to establish electrical contact between portions of aluminum foils
on the front and rear sides, so as to form the antenna coil. Here,
the crimping process refers to a process for establishing physical
contact between portions of aluminum foils constituting the circuit
pattern layer, by destroying the resin film as the base material
and the adhesive layer by means of a drill, a file, ultrasonic wave
or the like. More specifically, the stacked body of the resin film
and the aluminum foil are brought into contact with a metal plate
having recesses and protrusions, and the stacked body is pressed by
a metal protrusion, whereby the resin film as the base material and
the adhesive layer are partially destroyed, allowing contact
between the surfaces of the aluminum foils, establishing electrical
conduction. FIGS. 7 and 8 are enlarged photographs of a partial
cross section of the stacked body including the resin film and the
aluminum foils that has been subjected to the actual crimping
process. FIG. 7 is a photomicrograph with the magnification of 48,
and FIG. 8 is a photomicrograph having the magnification of 160.
FIGS. 9 and 10 are schematic illustrations of the cross sectional
structures corresponding to the photographs of FIGS. 7 and 8.
[0088] As can be seen from FIGS. 9 and 10, surfaces of aluminum
foils forming the circuit pattern layer 13 extending on both sides
of adhesive layer 12 and resin film base material 11 are locally
brought into contact with each other at the pressure contact
portion 13a.
[0089] The structure and the method of manufacturing an antenna
coil for an IC card in accordance with the present invention has
been described. The following steps are continuously performed to
provide the final product, that is, the IC card. IC chips are
mounted on areas 13c and 13d of circuit pattern layer 13 of antenna
coil 1 for the IC card shown in FIG. 1. Thereafter, a covering
layer such as a white PET may be stacked by hot melt coating, for
example, on the surface of the stacked body of aluminum foil and
the resin film. The covering layer is not limited to white, and a
well known color pigment, an extender pigment, metallic pigment
such as aluminum flake, a known resin, varnish, vehicle or the like
may be used. Further, a component employed in a known IC card such
as a printed layer, a magnetic recording layer, a magnetic
intercepting layer, an overcoating layer, a vapor deposited layer
or the like may be laminated as needed.
[0090] FIG. 11 is a partial cross section taken along the direction
of the line II-II of FIG. 1, showing an antenna coil for an IC card
in accordance with another embodiment of the present invention.
[0091] As can be seen from FIGS. 1 and 11, antenna coil 1 for an IC
card includes a resin film base material 11, adhesive layers 12
formed on both surfaces of resin film base material 11, primer coat
layers 15 as underlying coating layers formed on the surfaces of
adhesive layers 12, and circuit pattern layers 13 formed of
aluminum foils, formed in accordance with a prescribed pattern on
the surfaces of primer coat layers 15. Circuit pattern layer 13 is
formed in an eddy pattern on the surface of the base material as
shown in FIG. 1. At an end portion of circuit pattern layer 13,
areas 13c and 13d are formed, on which IC chips are mounted. The
circuit pattern layer represented by the dotted line in FIG. 1 is
positioned on the rear surface of base material 11. The circuit
pattern layer 13 formed on the surface of base material 11 is in
contact with the circuit pattern layer 13 formed on the rear
surface of base material 11 to be electrically conductive at
pressure contact portions 13a and 13b, respectively. The contact is
attained by partially destroying the base material 11, adhesive
layers 12 and primer coat layers 15 by the crimping process.
[0092] As the material of the primer coat layer, at least one
selected from epoxy based primer, an acrylic primer, a vinyl
chloride-vinyl acetate copolymer based primer and the like may be
used. Preferably, the primer coat layer has the thickness of at
least 0.1 .mu.m and at most 5.0 .mu.m. When the thickness of the
primer coat layer is smaller than 0.1 .mu.m, blocking tends to
occur. When the thickness of the primer coat layer exceeds 5 .mu.m,
the antenna coil comes to have large electric resistance, making
conduction with other components or lines insufficient, possibly
causing heat build up or malfunction.
[0093] Another embodiment of the method of manufacturing an antenna
coil for an IC card in accordance with the present invention will
be described in the following. FIGS. 12 to 16 are partial cross
sectional views showing the steps of manufacturing the antenna coil
for an IC card in accordance with this another embodiment of the
present invention. FIGS. 12 to 16 are cross sections taken along
the direction of the line II-II of FIG. 1.
[0094] Referring to FIG. 12, a primer coat layer 15 is formed on
one surface of each of the two aluminum foils 130. In this manner,
before adhering the aluminum foil 130 to the resin film base
material 11, primer coat process is performed at least partially
and preferably on one surface of aluminum foil 130, to form a
primer coat layer. The method of forming the primer coat layer is
not particularly limited and it can be formed by brush coating,
dipping, roller coater, bar coater, doctor blade, spray coating,
printing or the like. Preferable method is gravure printing.
[0095] After the primary coat layer is formed, it is preferred that
drying and curing process is performed at a temperature of about
50.degree. C. to about 250.degree. C. for about 5 to about 300
seconds, for sufficient curing.
[0096] Referring to FIG. 13, adhesive layers 12 are formed on
opposing surfaces of resin film base material 11, and by the
adhesive layers 12, one surface of respective ones of the aluminum
foils 130 on which primer coat layer 15 has been formed is fixed on
each surface of resin film base material 11. In this manner, a
stacked body of aluminum foils 130 and resin film base material 11
is prepared.
[0097] Referring to FIG. 14, resist ink layer 14 is printed on the
surface of each aluminum foil 130 to have prescribed eddy patterns
in accordance with the specification of the antenna coil. After
printing, curing process of the resist ink layer 14 is
performed.
[0098] Referring to FIG. 15, using the resist ink layers 14 as a
mask, aluminum foils 130 are etched, whereby circuit pattern layers
13 are formed.
[0099] Thereafter, as shown in FIG. 16, resist ink layers 14 are
removed.
[0100] Finally, using a metal plate having recesses and protrusions
and a metal protrusion, crimping process is performed at a
prescribed region of circuit pattern layers 13, so as to form the
contact portion or pressure contact portion 13a of the circuit
pattern layer, as shown in FIG. 11. In this manner, an antenna coil
1 for an IC card in accordance with the present invention is
completed.
EXAMPLE 1
[0101] On opposing surfaces of a base material of low profile
polyethylene naphthalate having the thickness of 50 .mu.m, aluminum
foils (an aluminum foil having the thickness of 30 .mu.m on one
surface and aluminum foil having the thickness of 20 .mu.m on the
other surface of the base material) having such a chemical
composition (mass %) as shown in Table 1 were adhered by dry
lamination method using a polyurethane based adhesive containing
epoxy, to form circuit pattern layers, whereby a stacked body was
prepared.
1TABLE 1 sample name Fe Si Cu Mn Mg Zn Ti Ga Al A 1.4 0.09 0.03 tr.
tr. tr. tr. tr. remaining part B 1 0.07 0.02 tr. tr. tr. tr. tr.
remaining part C 0.5 0.1 0.05 tr. tr. tr. tr. tr. remaining part D
0.03 0.05 0.01 tr. tr. tr. tr. tr. remaining part
[0102] In Table 1, "tr" represents that it is smaller than 0.01
mass %.
[0103] For preliminary evaluation, mechanical properties of the
thus obtained stacked body was evaluated by tension test. Results
are as shown in Table 2. In Table 2, tensile strength and proof
stress are represented by the unit of N/15 mm width.
2 TABLE 2 longitudinal direction lateral direction sample tensile
proof elongation tensile proof elongation name strength stress (%)
strength stress (%) A 220 60 81 215 62 82 B 213 55 69 212 55 73 C
203 53 64 204 52 65 D 201 51 55 203 47 55
[0104] As a preliminary evaluation of emboss processability,
bursting strength was evaluated by applying pressure. Measurement
of burst strength was performed in accordance with the method
specified in JIS P8112. Results are as shown in Table 3.
3 TABLE 3 sample bursting strength name (N/cm.sup.2) A 186 B 181 C
171 D 165
[0105] From Tables 1 to 3, it can be understood that tensile
strength, elongation and bursting strength attain higher as iron
content is higher. Therefore, in stacked bodies (samples A and B)
to which aluminum foil with low aluminum purity are adhered,
possibility of tearing or possibility of circuit disconnection is
lower even when emboss processing or the like is performed during
manufacturing of the IC card or when deforming stress is applied
while the IC card is used, as compared with the samples having
higher aluminum purity (sample D).
[0106] Thereafter, on both surfaces of the stacked body, a print
pattern such as shown in FIG. 1 was printed using a resist ink of
the following composition by helioklisho gravure printing. After
printing, the resulting body was irradiated with an ultraviolet ray
lamp having the exposure of 480 W/cm for 15 seconds to cure the
resist ink, and thus a resist ink layer was formed.
[0107] Ink composition was as follows.
[0108] Beckacite J-896 (Rogin-maleic acid resin manufactured by
Dainippon Ink & Chemicals): 21 parts by weight
[0109] 2-acryloyl hexyethylhexa hydrophtalic acid: 25 parts by
weight
[0110] Unidic V-5510 (a mixture of prepolymer and monomer
manufactured by Dainippon Ink & Chemicals): 8 parts by
weight
4 IRGACURE 184: 3 parts by weight Ethyl acetate: 28 parts by weight
Denatured alcohol: 12 parts by weight Phthalocyanine blue: 1 parts
by weight Silica: 2 parts by weight.
[0111] The stacked body with the resist ink layer formed in the
above described manner was dipped in a hydrochloric acid solution,
which was diluted at a volume ratio of 1 (hydrochloric acid): 3
(pure water), under the etching conditions (temperature, time) as
shown in Table 4, so as to etch the aluminum foil, and the circuit
pattern layer in accordance with the prescribed pattern was formed.
Thereafter, the stacked body was dipped in a sodium hydroxide
solution of 1% at 20.degree. C. for 10 seconds, so as to remove the
resist ink. Thereafter, the stacked body was dried with hot air of
70.degree. C., whereby a stacked body such as shown in FIG. 6 was
fabricated.
[0112] By performing the crimping process using a metal plate
having recesses and protrusions and a metal protrusion at a
prescribed position of the stacked body obtained in this manner, an
antenna coil for an IC card such as shown in FIG. 2 was
fabricated.
[0113] In the step of etching the aluminum foil described above,
etching characteristics of samples A, B, C and D were
evaluated.
[0114] Table 4 represent line widths of aluminum of respective
samples obtained under respective etching conditions.
5 TABLE 4 sample etching condition aluminum line name temp.
(.degree. C.) time (sec.) width (mm) A 45 124 0.3 B 45 124 0.31 C
45 124 0.39 D 45 124 >0.60 A 40 124 0.37 B 40 124 0.37 C 40 124
0.43 D 40 124 >0.60 A 35 124 0.38 B 35 124 0.39 C 35 124 0.46 D
35 124 >0.60 A 45 70 0.41 B 45 70 0.41 C 45 70 0.47 D 45 70
>0.60 A 45 52 0.45 B 45 52 partially left C 45 52 almost fully
left D 45 52 fully left
[0115] From Table 4, it can be seen that when etching temperature
(etchant temperature) is 45.degree. C., the etching time necessary
to attain the target line width (0.40 mm) was about 124 seconds for
sample C, and about 70 seconds for samples A and B. For sample D
(comparative example), the line width was wider than 0.6 mm even
after the etching of 124 seconds. From these results, it can be
understood that efficient production of an antenna coil for an IC
card is possible by samples A and B that use the aluminum foil
containing iron within the range of the present invention. In
Sample A, etching to the line width of 0.45 mm was possible by the
etching time of 52 seconds.
[0116] Further, influence of etching temperature was studied while
maintaining the etch time constant at 124 seconds. Satisfactory
etching was possible for samples A and B even when etching
temperature lowers, while line width became wider in sample D, and
therefore it is understood that etching amount was insufficient
when the temperature was decreased.
[0117] FIGS. 17-20 are photographs with the magnification of about
35 of surfaces of samples A and C etched at a temperature of
35.degree. C. for 124 seconds and samples A and C etched at a
temperature of 45.degree. C. for 52 seconds, respectively. In FIGS.
17-19, the linear circuit pattern layers look rough with
black-white mixed pattern and the resin film base material exposed
by etching aluminum foil looks gray. In FIG. 20, the surface of
aluminum foil after the resist ink layer was removed looks black
with white dots and the surface of aluminum foil left without being
etched looks gray.
EXAMPLE 2
[0118] On opposing surfaces of base materials formed of resin films
of such thickness and materials as shown in Table 5, foils of such
thickness and material as shown in Table 5 were adhered by dry
lamination method using the adhesives of the materials as shown in
Table 5, to form circuit pattern layers, whereby stacked bodies
were fabricated. On both sides of each of the stacked body prepared
in this manner, a print pattern such as shown in FIG. 1 was printed
using a resist ink having such a composition as described below by
helioklisho gravure printing. After printing, the resulting bodies
were irradiated with an ultraviolet lamp having the exposure of 480
W/cm for 15 seconds to cure the resist ink, thereby resist ink
layers were formed.
[0119] Ink composition was as follows.
[0120] Beckacite J-896 (Rogin-maleic acid resin manufactured by
Dainippon Ink & Chemicals): 21 parts by weight
[0121] 2-acryloyl hexyethylhexa hydrophtalic acid: 25 parts by
weight
[0122] Unidic V-5510 (a mixture of prepolymer and monomer
manufactured by Dainippon Ink & Chemicals): 8 parts by
weight
6 IRGACURE 184: 3 parts by weight Ethyl acetate: 28 parts by weight
Denatured alcohol: 12 parts by weight Phthalocyanine blue: 1 parts
by weight Silica: 2 parts by weight.
[0123] The stacked body having the resist ink layer formed in the
above described manner was dipped in a ferric chloride solution of
35% at 40.degree. C. for 5 minutes to etch the aluminum foil, and a
circuit pattern layer in accordance with a prescribed pattern was
formed. Thereafter, the stacked body was dipped in a sodium
hydroxide solution of 1% at 20.degree. C. for 10 seconds, so as to
remove the resist ink layer. The stacked body was dried with hot
air of 70.degree. C., whereby a stacked body such as shown in FIG.
6 was fabricated.
[0124] By performing the crimping process using a metal plate
having recessed and protruded portions and a metal protrusion at a
prescribed position of the stacked body obtained in this manner, an
antenna coil for an IC card such as shown in FIG. 2 was
fabricated.
[0125] Antenna coils of the thus obtained samples were held in a
thermostat of 150.degree. C. for 30 minutes, taken out therefrom
and cooled to the room temperature. Thereafter, appearances of the
antenna coils were visually observed, and thermal contraction
coefficient was measured by measuring the length of the base
materials, to evaluate dimensional accuracy. Results of evaluation
are as shown in Table 5.
7 TABLE 5 circuit pattern layer base material front side rear side
thermal contraction Sample thickness adhesive thickness thickness
coefficient (%) overall No. material (.mu.m) material material
(.mu.m) material (.mu.m) MD TD appearance evaluation 1 low profile
38 epoxy Al 30 Al 10 0.13 0.04 .largecircle. .largecircle. PET
containing PU 2 low profile 38 epoxy Al 30 Al 10 0.08 0.02
.largecircle. .largecircle. PEN containing PU 3 general 38 epoxy Al
30 Al 10 1.52 0.23 X X PET containing PU 4 general 38 epoxy Al 30
Al 10 0.41 0.08 .DELTA. .DELTA. PEN containing PU 5 low profile 50
epoxy Al 20 Al 20 -- -- -- -- PET containing PU 6 low profile 50
epoxy Cu 18 Cu 18 -- -- -- -- PET containing PU 7 CPP 38 epoxy Al
30 Al 10 -- -- X X containing PU 8 polyimide 25 PU Cu 18 Cu 18 --
-- .DELTA. .DELTA.
[0126] The antenna coils of Sample Nos. 1 and 2 in accordance with
the present invention had small thermal contraction coefficient and
good appearance. By contrast, in the antenna coils of Sample Nos. 3
and 4, the thermal contraction coefficient was small in the TD
(traverse direction: direction vertical to the direction of
rolling), while it was high in MD (machine direction: rolling
direction), and it was recognized that dimensional accuracy of the
circuit pattern layer was degraded. In the antenna coil of Sample
No. 7, cast propylene was used as the base material, and hence it
melted when held at 150.degree. C. for 30 minutes. In Sample No. 8,
polyimide film was used as the base material, polyurethane adhesive
(PU) not containing epoxy resin was used as the adhesive, and
copper foil was used as the material for the circuit pattern layer.
Warp was generated while it was left at the room temperature, and
appearance was not satisfactory.
[0127] In Table 5, appearance evaluation are as follows:
satisfactory appearance: , crease and flexure observed: , and
deformed and unusable: .
[0128] Using antenna coils of Sample Nos. 1, 2, 5, 6 and 8 of Table
5, conduction characteristics of portions that had been subjected
to crimping process were evaluated.
[0129] For Sample Nos. 1, 2 and 5, high temperature retention test
at a temperature of 180.degree. C. for 1 minute and in addition at
a temperature of 150.degree. C. for 1 hour with the initial
conduction resistance at the crimping portion of 0.04.OMEGA., and
heat press test at a temperature of 120.degree. C. for 5 minutes
with the pressure of 5 kg/cm.sup.2 were performed, and the
conduction resistance was maintained at 0.04.OMEGA.. For Sample No.
6, in the high temperature retention test with the initial value of
conduction resistance at the crimping portion being 0.04.OMEGA.,
the conduction resistance was maintained at 0.04.OMEGA., while in
the heat press test, the crimping portion became non-conductive. In
Sample No. 8 with the initial value of conduction resistance at the
crimping portion being 0.04.OMEGA., crimping portion became
non-conductive in both of the two tests described above.
EXAMPLE 3
[0130] As shown in FIG. 12, epoxy coating agent No. 8800
(manufactured by Tanaka Chemical Kabushiki Kaisha) was applied to
have the thickness of 1.5 .mu.m after drying as the primer coat
processing, on one surface of each of aluminum coils (tape-shaped)
(JIS IN30-O) having the thickness of 30 .mu.m and 20 .mu.m,
respectively, as metal foils 130, and thereafter dried and cured at
a temperature of 200.degree. C. for 30 seconds. In this manner,
primer coat layer 15 was formed on one surface of each of the two
aluminum foil coils.
[0131] Thereafter, referring to FIG. 13, one surface of the
aluminum foil coil having the thickness of 30 .mu.m on which primer
coat layer 15 had been formed was adhered by an adhesive layer 12
to one surface of a PET film having the thickness of 38 .mu.m as a
resin film base material 11, and one surface of the aluminum foil
coil having the thickness of 20 .mu.m on which primer coat layer 15
had been formed was adhered to the other surface of the PET film,
whereby a stacked body coil material was fabricated. An
epoxy-urethane dry laminate adhesive AD76P1 (manufactured by
Toyo-Morton, Ltd.) was used as the adhesive, and the amount of
adhesive applied was 4 g/m.sup.2 by weight after drying.
[0132] Referring to FIG. 14, on the other surface of the aluminum
foil coil as the metal foil 130, resist ink layer 14 having such a
circuit pattern as shown in FIG. 1 was printed continuously and
repeatedly. As the resist ink, the material similar to that used in
Example 2 was used, and the amount of applied resist ink was 5
g/m.sup.2 by weight after drying.
[0133] Using resist ink layer 14 formed in this manner as a mask,
the aluminum foil was etched to form a circuit pattern layer 13 as
shown in FIG. 15. Ferric chloride solution was used as the
etchant.
[0134] Thereafter, as shown in FIG. 16, resist ink layer 14 was
removed by using sodium hydroxide solution.
[0135] Finally, crimping process for establishing electrical
conduction between the front end and back was performed using a
metal plate having recesses and protrusions and a metal protrusion,
at a prescribed position on the surfaces of the stacked body coil
material, whereby a tape-shaped material for the antenna coils for
IC cards having such a cross section as shown in FIG. 11 was
fabricated.
[0136] Thereafter, the tape-shaped material of the antenna coils
for IC cards was rolled to a coil with a tension of
1.96.times.10.sup.2N/m (width) by a take up apparatus.
EXAMPLE 4
[0137] The tape-shaped material of antenna coils for IC cards was
fabricated through the same process steps as Example 3, except that
an epoxy-melamine coating agent No. 952-H (Manufactured by Tanaka
Chemical Kabushiki Kaisha) was applied to the thickness of 2 .mu.m
after drying, as the primer coat process.
EXAMPLE 5
[0138] The tape-shaped material of antenna coils for IC cards was
fabricated through the same process steps as Example 3, except that
a PEN film having the thickness of 38 .mu.m was used as the resin
film base material.
EXAMPLE 6
[0139] The tape-shaped material of antenna coils for IC cards was
fabricated through the same process steps as Example 3, except that
an epoxy coating agent No. 8800 (manufactured by Tanaka Chemical
Kabushiki Kaisha) was applied to have the thickness of 0.05 .mu.m
after drying as the primer coat process.
EXAMPLE 7
[0140] The tape-shaped material of antenna coils for IC cards was
fabricated through the same process steps as Example 3, except that
an epoxy coating agent No. 8800 (manufactured by Tanaka Chemical
Kabushiki Kaisha) was applied to have the thickness of 6 .mu.m
after drying as the primer coat process.
Reference Example 1
[0141] A tape-shaped material of antenna coils for IC cards was
fabricated through the same process steps as Example 3, except that
the primer coat process was not performed on the aluminum foil coil
material.
[0142] Thus prepared tape-shaped materials were held at prescribed
temperatures shown in Table 6 for 48 hours, and thereafter, end
portions of each tape-shaped material was held by ends to evaluate
whether there was a blocking. Evaluation was in accordance with the
following indexes.
[0143] Evaluation 5: overlapping portions are separated smooth
without the necessity of pulling, when the tape-shaped material is
unrolled.
[0144] Evaluation 4: though there is a faint sound when the
tape-shaped material is unrolled, overlapping portions were
separated without the necessity of applying a particularly strong
force.
[0145] Evaluation 3: overlapping portions were separated only when
a force is applied to unroll the tape-shaped material, though the
force is not very strong.
[0146] Evaluation 2: though overlapping portions were separated
when force was applied to unroll the tape-shaped material, the
material was partially damaged.
[0147] Evaluation 1: overlap portions were tightly adhered and not
separated even when force was applied to unroll the tape-shaped
material.
[0148] Of these evaluations, evaluation 5 is the highest for the
product of the tape-shaped material for antenna coils. In order to
prevent any trouble in the subsequent manufacturing line for IC
cards, the product must have the evaluation of 4 or higher.
[0149] Further, electrical resistance value of the crimping
portions of the prepared tape-shaped materials were measured by a
tester.
[0150] Further, appearances of the circuit pattern layers obtained
through etching were evaluated.
[0151] The evaluation was performed by visually observing defective
etching including disconnection, thinning and peeling of the
circuit pattern layers. Products without any defective etching was
evaluated as "good", and products that may possibly have problems
in performance as an antenna coil product was evaluated as "not
good."
[0152] The results are as shown in Table 6.
8 TABLE 6 resistance blocking evaluation value (in 5 stages)
evaluation held at held at at crimping etching material 40 .degree.
C. 60.degree. C. portion appearance Ex. 3 5 5 at most 0.1 good
.OMEGA. Ex. 4 5 5 at most 0.1 good .OMEGA. Ex. 5 5 5 at most 0.1
good .OMEGA. Ex. 6 4 4 at most 0.1 good .OMEGA. Ex. 7 5 5 0.8
.OMEGA. good Reference 2 1 at most 0.1 good Ex. 1 .OMEGA.
[0153] From Table 6, it can be understood that Examples 3 to 7 have
the blocking evaluation of 4 or higher, while blocking evaluation
is 1 for the Reference Example 1 that does not have the primer coat
processing. In Example 6, as the thickness of the primer coat layer
was smaller than 0.1 .mu.m, blocking is more likely as compared
with Examples 3 to 5, so that blocking evaluation is slightly
lower. In Example 7, as the primer coat layer has the thickness
larger than 5 .mu.m, electrical resistance value of the crimping
portion was increased.
[0154] Although the present invention has been described and
illustrated in detail, it is clearly understood that the same is by
way of illustration and example only and is not to be taken by way
of limitation, the spirit and scope of the present invention being
limited only by the terms of the appended claims.
* * * * *